If you enable flexstep in the TRX's global settings it will tune with half the step size of what are set in its bandplan.
The user manual says:
450.00625-512.000 MHz.......................(in 6.25 kHz steps/FM)
But the latest bandplan I got from Whistler to edit has the US one set as:
450.003125 | 470.000000 | 3.125 | FM |
So I would say you have different firmware versions in the two scanners. Try loading the latest firmware to the one you have bandplan issues with. With each new firmware version there's a new EZ-Scan program that has to be used.
As the latest firmware has 3.125KHz as a step size, then when enable flexstep it will do it's smallest step that might be 2.5KHz.
You have to use service software to tune the frequency oscillator in the scanner if it actually have drifted off frequency. If you have enabled ZM ZeroMatic it will not open squelch on any signals off frequency, so try that disabled. If you listen to a data signal with the squelch set to zero and in analog mode, then enable flexstep and in tune mode Fn+0 you tune back and forth and try to hear where the middle of the signal are, if it sounds the same if you go one or two steps lower as when you go one or two steps higher in frequency.
/Ubbe